Previous moving beltways have suffered certain disadvantages.
If they are to be a constant speed beltway the surface has either been very heavy belting or metal treads located on a carrier frame and each of these are inherently expensive and also provide mechanical problems in siting, in that when they are to return they need a substantial diameter roller, as the radius about which they can turn is large. This may involve the building of a pit or the like at each end of the beltway to receive the rollers.
A further major problem with moving beltways, quite generally but particularly if they are to be of variable speed or are long has been the translation of the user between a stationary position and the beltway and between adjacent parts of a beltway. This latter aspect has been considered most serious for two reasons. Firstly such transistions are normally required to be effected where the beltway is one which has a variable speed and thus the transition is occurring at a higher absolute speed than is the case with moving onto or off a standard beltway moving at a slow speed.
This means that whilst the relative speed between the two adjacent sections of beltway are relatively small, the belts or the like comprising the surfaces of the beltway are both travelling at relatively high speeds adjacent to the surrounding ground or wall defining the sides of the beltway.
Thus, should, for example, a user fall or an article attached to a person, such as part of a shoe a trailing portion of a garment or the like be caught between the belt or the plate or comb at the transition then the likelihood of injury is substantially greater than would be the case if the same accident occured on a slower speed beltway section.
There have been proposed ways in which to attempt to overcome these problems, but they have not been satisfactory and have not been commercially adopted.
They include the use of transfer plate sections which are movable in a plane normal to the beltways and the concept of short lengths of narrow belts which overlap in the direction of movement thereof, and belts which are at different levels so that a user has to physically step from one belt upwardly or downwardly to the next adjacent belt. Also where the belts are ribbed, which has normally been the case, the transfer area must include combs, and where the belts are heavy and are passing over relatively large diameter rollers, it has been practically, extremely difficult if not impossible to maintain accurate narrow spacings between the combs and the belt when the belt is travelling at a high speed.